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Suppose nominal GDP was $360 billion in 1990 and $450 billion in 2000. The appropriate price index was 100 in 1990 and 112.5 in 2000. Between 1990 and 2000 real GDP Select one: O a. Increased by $60 billion O b. Decreased by $30 billion O c. Increased by $40 billion O d. Increased by $50 billion